Electrolytic cell structure

ABSTRACT

An electrolytic cell is made up of a stack of polysulfone plates faced with sheets of platinum bonded thereto by silicone rubber and mechanically secured to their plates by Teflon screws having heads serving as spacers between opposed platinum sheets.

United States Patent Fletcher et al.

[ June 24, 1975 [54] ELECTROLYTIC CELL STRUCTURE 2,468,022 4/1949 Blueet al 204/290 R X 3,402,l l7 9/1968 Evans 204/286 X 1 Inventors JamesFletch", Adfmmstrator of 3,408,280 10/1968 Preiser 204/286 x theNatloflal Aeronautlcs and Space 3,674,675 7/1972 Leaman 204/290 RAdministration, with respect to an invention of David F. Putnam, OTHERPUBLICATIONS M rtle Creek, Gr Richard L, Bass, S. L, et al., Siliconesas Electrical Insulating Vaughan, Long Beach, Calif. Materials, TheElectrochemical Society, Preprint [22] Filed: Feb. 8, 1974 90-19,lO/1946, pp. 266-272.

[21] Appl. No.: 440,916 Primary Examiner-John H. Mack AssistantExaminer-W. 1. Solomon 52 us. c1. 204/267; 204/242; 204/279; Agen"Osborn;

204/286; 204/290 R g [51] Int. Cl B0lk 3/00 158 Field 6: Search 204/267,269, 279, 286, [57] ABSTRACT 204 290 R, 242 An electrolytic cell is madeup of a stack of polysuL fone plates faced with sheets of platinumbonded 56] R fere e Ci d thereto by silicone rubber and mechanicallysecured UNITED STATES PATENTS to their plates by Teflon screws havingheads serving 745,412 12 1903 Blackman 204 286 as spacers betweenOpposed platmum Sheets 806,413 12/1905 Kother 204/286 5 Claims, 3Drawing Figures g; u I8 22 22 22/ PATENTEDJUN24 I975 3.891. 533

SHEET 1 III FIG. 1

SHEET PATENTEDJUN 24 I975 m O\\\ H 2 MW 2 L J 2 H 2 2 I, n f 2 2 5 B 2\FIG. 2

FIG. 3

1 ELECTROLYTIC CELL STRUCTURE The invention described herein was made inthe performance of work under a NASA contract and is subject to theprovisions of Section 305 of the National Aeronautics and Space Act of1958, Public Law 85-568 (72 Stat. 435; 42 USC 2457).

BACKGROUND OF THE INVENTION This invention is in the field ofelectrolytic cells and particularly to the construction of elementsthereof.

Electrolytic cells are known wherein spaced sheets of insulatingmaterial define liquid flow paths therebetween and wherein each sheet isprovided with a conductive face exposed to the flow path. Such priordevices, however, have been subject to disadvantages in that theconductive or metallic faces have been in the form of sheets that couldseparate from their supporting plate during operation and buckle intoelectrical contact with an opposed sheet, thus rendering the cellinoperative. Furthermore, it is necessary to protect the edges of theconductive sheets from corrosive attack and it has heretofore beenproposed to employ accurately machined recesses in the supporting platesto encompass and seal against the edges of the conducting sheets.

SUMMARY OF THE INVENTION The present invention seeks to eliminate theforegoing objections by bonding and clamping the conductive sheets tothe faces of their supporting plates and renders construction of suchcells considerably simpler by providing clamping screws for the metallicsheets, which screws are of insulating material and further serve asspacers predetermining the transverse dimensions of the flow pathsthrough the cell.

It is, therefore, an object of this invention to provide a simpleelectrolytic cell assembly wherein insulating screws serve the functionsof holding conductive sheets to their supporting plates and alsofunction as spacers between adjacent conductive plates.

It is a further object of this invention to provide an electrolytic cellas set forth wherein the conductive sheets are bonded and edge sealed totheir supporting plates without the necessity of special machiningoperations.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an end view of anelectrolytic cell constructed in accordance with the present invention;

FIG. 2 is an enlarged sectional view taken on the line 2-2 of FIG. I;and

FIG. 3 is a bottom view of upper electrode assembly shown in FIG. 2.

DESCRIPTION OF A PREFERRED EMBODIMENT As shown in FIG. 1, theelectrolytic cell of the present invention comprises a pair of outersupport plates 2 and a plurality of intermediate plates 4. Each of theplates is provided with a laterally extending ear 6 for a purpose to bedescribed. An assembly of the plates is stacked as shown and rubber orsilicone rubber gaskets 8 extend at least around the peripheries ofadjacent plates to seal the spaces therebetween with the plates inspaced parallel relationship to thereby define flow paths between theplates for flow of liquids to be treated. The inner faces of plates 2and both faces of plates 4 are covered with a sheet of conductive metalwhich extends outwardly therefrom on the ears 6 to where they areconnected to suitable terminal connectors 10 whereby the conductivesheets may be suitably connected to a source of electrical power. Thefeatures thus far described are more or less conventional and will notbe described in further detail except to point out that the stack ofplates is held in assembled relation by suitable through bolts 12 andthe cell is provided with an inlet fitting 14 and an outlet fitting (notshown). The inlet fitting communicates with a passageway 15 leading toone end of the flow path between the plates and suitable ports 25through the plates 4 provide for connecting the flow paths betweenadjacent plates in series or parallel relationship.

Referring now to FIG. 2, the plates 4 are shown as being of insulatingplastic material, preferably polysulfone suitable for many specializeduses for the cell. Each of the conductive metal sheets referred to isidentified by numeral 16 and each is preferably a sheet of platinum ofabout 2 mil thickness. Each of the sheets 16 is bonded to its supportplate 4 by a layer of silicone rubber material 18. The silicone rubberis preferably spread onto the surfaces of plates 2 and 4 while wet andthe platinum sheet 16 is then placed thereon and held clamped inposition until the rubber material sets, thus effecting a bond betweenthe platinum sheet and plate 2 or 4, which bond conforms precisely tothe surfaces of each. As shown in FIG. 2, the silicone rubber material18 extends to the outer edges of the sheets 16 and effects a completeseal in that region to protect the edges of the platinum sheets againstelectrolytic attack.

In addition to the bonding effect of the silicone rubber 18, theplatinum sheets 16 are further mechanically clamped to their supportingplates 4 by headed screws 20 made of insulating material immune toattack by the liquids being processed. The screws 20 are preferably madeof tetrafluoroethylene, commonly known as Teflon. The screws 20 areprovided with enlarged heads 22 overlying the platinum sheets 16 and allheads 22 are of the same axial length whereby they may extend toward andinto contact with an adjacent platinum sheet 16 to thus maintain properspacing between those plates to predetermine the transverse dimension ofthe flow path between plates 16, identified by numeral 24. Preferably,the screws 20 extend threadedly into corresponding threaded openings 26in plates 2 and 4. As evident from FIG. 2, the screws 20 in adjacentplates 4 are laterally offset whereby the screw heads from both platesextend into and across the same flow path 24 without interference fromeach other.

It is to be understood that essentially the same construction describedwith reference to FIG. 2 is provided between plates 2 and 4. Thus, allof the plates 4 may be of identical construction and the same is true ofall of the plates 2. The silicone rubber gaskets 8 previously referredto extend at least around the periphery of the plates 2 and 4 with thescrews 20 being inwardly therefrom. The screws 20 may be dispersed asdesired throughout the areas of the platinum sheets 16 and function notonly to maintain adhesion between sheets 16 and bonding layer 18 butalso serve to prevent any buckling or warping of the sheets 16 away fromtheir supporting plates. It is to be understood that the gaskets 8 maybe suitably configured or additional internal gaskets may be provided toestablish any desired shape of flow path between plates. After assemblyof the entire stack of plates, as shown in FIG. 1, the assembly is heldin clamped relationship by the through bolts 12 which preferably extendthrough the stack of plates, through enlarged openings in platinumsheets 16 and through the peripheral gaskets 8 whereby the screws 12 arecompletely insulated from the electrical circuits of the cell. On theother hand, the through bolts 12 may be of nonconductive or insulatingmaterial.

While a single specific embodiment of the invention has been shown anddescribed, it is to be understood that the same is merely illustrativeof the principles of the invention and other forms may be resorted towithin the scope of the appended claims.

We claim:

1. in an electrolytic cell assembly comprising a plurality of spacedparallel insulating plates, with adjacent plates defining flow pathstherebetween, said plates having electrically conductive sheets securedthereto, the improvement comprising:

adhesive means for securing said conductive sheets to said plates andfor sealing edges of said conductive sheets thereby protecting saidconductive sheets from electrolytic attack; headed screw means ofinsulating material for securing each of said conductive sheets to itsrespective plate and for preventing buckling of said conductive sheet bymaintaining adhesion between said conductive sheet, said adhesive meansand said insulating plate and for maintaining a predetermined spacingbetween said plates; and resilient gasket means between said adjacentplates defining predetermined flow paths therebetween.

2. An electrolytic cell assembly as defined in claim 1 wherein saidadhesive means comprises a layer of silicone rubber of sufficientthickness to insure sealing of said conductive sheet edges uponcompression.

3. An electrolytic cell as defined in claim 1 wherein said plates are ofpolysulfone and said conductive sheets are of platinum.

4. An electrolytic cell assembly as defined in claim 3 wherein saidheaded screws are of tetrafluoroethylene.

5. An electrode assembly for an electrolytic cell comprising:

a plate of insulating material;

a thin sheet of platinum overlying at least one face of said plate andsecured thereto by a layer of silicone rubber;

screw means of insulating material for securing said sheet to said plateand for preventing buckling of said thin sheet by maintaining adhesionbetween said thin sheet, plate, and layer of silicone; said screw meanshaving a head extending outward from said thin sheet a predetermineddistance and engaging an adjacent metal sheet to maintain apredetermined spacing between said adjacent plates;

said layer of silicone rubber extending to the edges of said sheet forbonding said sheet to said plate and for sealing the edges of said sheetagainst electrolytic attack.

1. IN AN ELECTROLYTIC CELL ASSEMBLY COMPRISING A PLURALITY OF SPACEDPARALLEL INSULATING PLATES, WITH ADJACENT PLATES DEFINING FLOW PATHSTHEREBETWEEN, SAID PLATES HAVING ELECTRICALLY CONDUCTIVE SHEETS SECUREDTHERETO, THE IMPROVEMENT COMPRISING: ADHESIVE MEANS FOR SECURING SAIDCONDUCTIVE SHEETS TO SAID PLATES AND FOR SEALING EDGES OF SAIDCONDUCTIVE SHEETS THEREBY PROTECTING SAID CONSDUCTIVE SHEETS FROMELECTROLYTIC ATTACK; HEADED SCREW MEANS OF INSULATING MATERIAL FORSECURING EACH OF SAID CONDUCTIVE SHEETS TO ITS RESPECTIVE PLATE AND FORPREVENTING BUCKLING OF SAID CONDUCTIVE SHEET BY MAINTAINING ING ADHESIONBETWEEN SAID CONDUCTIVE SHEET, SAID ADHESIVE MEANS AND SAID INSULATINGPLATE AND FOR MAINTAINING A PREDETERMINED SPACING BETWEEN SAID PLATES;AND RESILIENT GASKET MEANS BETWEEN SAID ADJACENT PLATES DEFININGPREDETERMINED FLOW PATHS THEREBETWEEN.
 2. An electrolytic cell assemblyas defined in claim 1 wherein said adhesive means comprises a layer ofsilicone rubber of sufficient thickness to insure sealing of saidconductive sheet edges upon compression.
 3. An electrolytic cell asdefined in claim 1 wherein said plates are of polysulfone and saidconductive sheets are of platinum.
 4. An electrolytic cell assembly asdefined in claim 3 wherein said headed screws are oftetrafluoroethylene.
 5. An electrode assembly for an electrolytic cellcomprising: a plate of insulating material; a thin sheet of platinumoverlying at least one face of said plate and secured thereto by a layerof silicone rubber; screw means of insulating material for securing saidsheet to said plate and for preventing buckling of said thin sheet bymaintaining adhesion between said thin sheet, plate, and layer ofsilicone; said screw means having a head extending outward from saidthin sheet a predetermined distance and engaging an adjacent metal sheetto maintain a predetermined spacing between said adjacent plates; saidlayer of silicone rubber extending to the edges of said sheet forbonding said sheet to said plate and for sealing the edges of said sheetagainst electrolytic attack.